Lubricating oil composition

ABSTRACT

A method of improving the seal compatibility and/or copper corrosion performance of lubricating oil compositions for the lubrication of the crankcases of an internal combustion engine, which method includes the step of adding to the lubricating oil compositions a minor amount of a non-hydrogenated (unsaturated) olefin polymer. Also described are lubricating oil compositions for engines and transmissions, which compositions contain sulphur and/or a salicylate soap and a minor amount of a non-hydrogenated (unsaturated) polymer, which compositions are compatible with nitrile rubber engine and transmission seals and copper-containing engine and transmission components.

FIELD OF THE INVENTION

This invention relates to a method of improving the seal-compatibilityperformance of lubricating oil compositions used in engine crankcasesand transmissions, particularly lubricating oil compositions havingsignificant sulphur and/or salicylate soap contents, and to lubricatingoil compositions having significant sulphur and/or salicylate soapcontents that exhibit enhanced seals compatibility performance inengines and transmissions containing nitrile rubber seal materials. Theinvention further relates to a method of improving copper corrosionperformance of lubricating oil compositions used in engine crankcasesand transmissions, particularly lubricating oil compositions havingsignificant sulphur contents, and to lubricating oil compositions havingsignificant sulphur contents that exhibit enhanced seals and coppercorrosion performance.

BACKGROUND OF THE INVENTION

Lubricating oil compositions used to lubricate internal combustionengines and transmissions contain a major amount of a base oil oflubricating viscosity, or a mixture of such oils, and additives used toimprove the performance characteristics of the oil. For example,additives are used to improve detergency, to reduce engine wear, toprovide stability against heat and oxidation, to reduce oil consumption,to inhibit corrosion, to act as a dispersant, and to reduce frictionloss. Some additives provide multiple benefits, such asdispersant-viscosity modifiers. Many base oils contain sulfur, and anumber of extremely effective additives conventionally used in engineand transmission lubricating oil compositions, including zinc dialkyldithiophosphates (ZDDP), certain molybdenum-sulfur compounds, ashlessdithiocarbamates and sulfonate and some phenate detergents, also containsulfur and contribute to the overall sulfur content of such formulatedlubricants.

Modern internal combustion engines and transmissions include numerousgaskets and other seals formed of nitrile rubber materials. Lubricantsulfur has been found to contribute to the deterioration of materials.Before certifying a crankcase lubricant for use in their engines, enginemanufacturers (oftentimes referred to as “original equipmentmanufacturers or “OEMs”) require passage of a number of performancetests, including tests for compatibility with engine seal materials. Itis also suspected that high levels of salicylate soap from salicylatedetergents may contribute to the deterioration of nitrile rubber sealmaterials, particularly in “low ash” lubricants. Therefore, it would bedesirable to provide a method of improving the seal compatibility oflubricating oil compositions, particularly lubricating oil compositionshaving significant sulfur contents and/or high levels of salicylatesoap, and lubricating oil compositions having significant sulfurcontents and/or high levels of salicylate soap, that provide improvedseal-compatibility performance.

Lubricant sulfur has been found to cause copper corrosion. Prior togranting certification, OEMs also require lubricating oil compositionsto pass a copper corrosion test. Therefore, it would be desirable toprovide a method of improving the copper corrosion performance oflubricating oil compositions, particularly lubricating oil compositionshaving significant sulfur contents, and lubricating oil compositionshaving significant sulfur contents that provide improved coppercorrosion performance.

SUMMARY OF THE INVENTION

It has now been found that the addition of a minor amount of anon-hydrogenated olefin (co)polymer, for example a polyisobutene, to alubricating oil composition improves the compatibility between thelubricating oil composition and nitrile rubber engine and transmissionseals, particularly in lubricating oil compositions containing asignificant amount of sulfur, such as a sulfur content greater thanabout 0.10 mass %, such as greater than about 0.15 mass %, particularlygreater than about 0.20 mass % and/or significant amounts of salicylatesoap from salicylate detergents, such as 9 or more, particularly 18 ormore, more particularly 24 or more mmols of salicylate soap per kilogramof finished lubricant. It has also been found that the addition of aminor amount of a non-hydrogenated olefin (co)polymer, for example apolyisobutene, to a lubricating oil composition improves the coppercorrosion performance of lubricating oil compositions, particularlylubricating oil compositions containing a significant amount of sulfur,such as a sulfur content greater than about 0.10 mass %, such as greaterthan about 0.15 mass %, particularly greater than about 0.20 mass %.

Therefore, in a first aspect, the invention is directed to a method ofimproving the seal compatibility performance of lubricating oilcompositions for the lubrication of an internal combustion engine orengine transmission, which method comprises adding to such lubricatingoil compositions a minor amount of a non-hydrogenated (unsaturated)olefin (co)polymer.

In a second aspect, the invention is directed to the method of the firstaspect in which the lubricating oil composition contains a significantsulfur content, such as a sulfur content greater than about 0.10 mass %,particularly greater than about 0.15 mass %, such as greater than about0.18 mass %, more particularly greater than about 0.20 mass %, andcomprises a major amount of oil of lubricating viscosity; a minor amountof at least one sulphur-containing additive, and from about 0.5 mass %to about 10.0 mass % of a non-hydrogenated olefin (co)polymer, whereinall mass percentages are based on the total mass of the lubricating oilcomposition.

In a third aspect, the invention is directed to the method of the firstaspect in which the lubricating oil composition comprises a major amountof oil of lubricating viscosity; a minor amount of at least onesalicylate detergent in an amount introducing into the lubricating oilcomposition 9 or more, particularly 18 or more, more particularly 24 ormore mmols of salicylate soap per kilogram of lubricating oilcomposition, and from about 0.5 mass % to about 10.0 mass % of anon-hydrogenated olefin (co)polymer, wherein all mass percentages arebased on the total mass of the lubricating oil composition.

In a fourth aspect, the invention is directed to a lubricating oilcomposition containing a significant sulfur content, such as a sulfurcontent greater than about 0.10 mass %, particularly greater than about0.15 mass %, such as greater than about 0.18 mass %, more particularlygreater than about 0.20 mass %, comprising a major amount of oil oflubricating viscosity; a minor amount of at least one sulphur-containingadditive, and from about 0.5 mass % to about 10.0 mass % of anon-hydrogenated olefin (co)polymer, wherein all mass percentages arebased on the total mass of the lubricating oil composition.

In a fifth aspect, the invention is directed to a lubricating oilcomposition comprising a major amount of oil of lubricating viscosity; aminor amount of at least one salicylate detergent in an amountintroducing into the lubricating oil composition 9 or more, particularly18 or more, more particularly 24 or more mmols of salicylate soap perkilogram of lubricating oil composition (finished lubricant), and fromabout 0.5 mass % to about 10.0 mass % of a non-hydrogenated olefin(co)polymer, wherein all mass percentages are based on the total mass ofthe lubricating oil composition.

In a sixth aspect, the invention is directed to a method of the secondaspect or a lubricating oil composition of the fourth aspect, whereinthe sulphur-containing additives are one or more of a metal salt of adihydrocarbyl dithiophosphate (e.g., ZDDP), a sulfonate detergent, asulfurized phenate detergent a molybdenum-sulphur compound and anashless dithiocarbamate.

In a seventh aspect, the invention is directed to a method of the secondaspect or a lubricating oil composition of the fourth aspect, whereinthe lubricating oil composition further contains a salicylate detergentin an amount introducing into the lubricating oil composition at leastabout 9 mmols of salicylate soap per kilogram of finished lubricant and,preferably, has a sulfated ash content of not greater than about 1.1mass %, more preferably no greater than 1.05 mass %.

In an eighth aspect, the invention is directed to a method of the thirdaspect or a lubricating oil composition of the fifth aspect, wherein thelubricating oil composition contains a significant sulfur content, suchas a sulfur content greater than about 0.10 mass %, particularly greaterthan about 0.15 mass %, such as greater than about 0.18 mass %, moreparticularly greater than about 0.20 mass %

In a ninth aspect, the invention is directed to a method of improvingthe copper corrosion performance of lubricating oil compositions for thelubrication of an internal combustion engine or engine transmission,which method comprises adding to such lubricating oil compositions aminor amount of a non-hydrogenated (unsaturated) olefin (co)polymer.

In a tenth aspect, the invention is directed to the method of the ninthaspect in which the lubricating oil composition contains a significantsulfur content, such as a sulfur content greater than about 0.10 mass %,particularly greater than about 0.15 mass %, such as greater than about0.18 mass %, more particularly greater than about 0.20 mass %, andcomprises a major amount of oil of lubricating viscosity; a minor amountof at least one sulphur-containing additive, and from about 0.5 mass %to about 10.0 mass % of a non-hydrogenated olefin (co)polymer, whereinall mass percentages are based on the total mass of the lubricating oilcomposition.

In an eleventh aspect, the invention is directed to the method of thetenth aspect wherein the sulphur-containing additives are one or more ofa metal salt of a dihydrocarbyl dithiophosphate (e.g., ZDDP), asulfonate detergent, a sulfurized phenate detergent a molybdenum-sulphurcompound and an ashless dithiocarbamate.

In a twelfth aspect, the invention is directed to a concentrate forpreparing a lubricating oil composition of the fourth aspect comprisingan oleaginous carrier, a non-hydrogenated olefin (co)polymer, and one ormore sulfur-containing additives.

In a thirteenth aspect, the invention is directed to a concentrate forpreparing a lubricating oil composition of the fifth aspect comprisingan oleaginous carrier, a non-hydrogenated olefin (co)polymer, and one ormore salicylate detergents.

Other and further objects, advantages and features of the presentinvention will be understood by reference to the followingspecification.

DETAILED DESCRIPTION OF THE INVENTION

The lubricating oil compositions of the present invention are forlubricating the crankcase of an internal combustion engine, preferably acompression-ignited (diesel) engine, more preferably acompression-ignited heavy duty diesel engine. Crankcase lubricating oilcompositions for a diesel application, in particular for heavy dutydiesel engines, have to be specifically formulated to meet theperformance requirements for such an application.

Oils of lubricating viscosity useful in the context of the presentinvention may be selected from natural lubricating oils, syntheticlubricating oils and mixtures thereof. The lubricating oil may range inviscosity from light distillate mineral oils to heavy lubricating oilssuch as gasoline engine oils, mineral lubricating oils and heavy dutydiesel oils. Generally, the viscosity of the oil ranges from about 2centistokes to about 40 centistokes, especially from about 4 centistokesto about 20 centistokes, as measured at 100° C.

Natural oils include animal oils and vegetable oils (e.g., castor oil,lard oil); liquid petroleum oils and hydrorefined, solvent-treated oracid-treated mineral oils of the paraffinic, naphthenic and mixedparaffinic-naphthenic types. Oils of lubricating viscosity derived fromcoal or shale also serve as useful base oils.

Synthetic lubricating oils include hydrocarbon oils and halo-substitutedhydrocarbon oils such as polymerized and interpolymerized olefins (e.g.,polybutylenes, polypropylenes, propylene-isobutylene copolymers,chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes),poly(1-decenes)); alkylbenzenes (e.g., dodecylbenzenes,tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes);polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenols); andalkylated diphenyl ethers and alkylated diphenyl sulfides andderivative, analogs and homologs thereof. Also useful are synthetic oilsderived from a gas to liquid process from Fischer-Tropsch synthesizedhydrocarbons, which are commonly referred to as gas to liquid, or “GTL”base oils.

Alkylene oxide polymers and interpolymers and derivatives thereof wherethe terminal hydroxyl groups have been modified by esterification,etherification, etc., constitute another class of known syntheticlubricating oils. These are exemplified by polyoxyalkylene polymersprepared by polymerization of ethylene oxide or propylene oxide, and thealkyl and aryl ethers of polyoxyalkylene polymers (e.g.,methyl-polyiso-propylene glycol ether having a molecular weight of 1000or diphenyl ether of poly-ethylene glycol having a molecular weight of1000 to 1500); and mono- and polycarboxylic esters thereof, for example,the acetic acid esters, mixed C₃-C₈ fatty acid esters and C₁₃ oxo aciddiester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils comprises theesters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkylsuccinic acids and alkenyl succinic acids, maleic acid, azelaic acid,suberic acid, sebasic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkylmalonic acids, alkenyl malonic acids) with avariety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycolmonoether, propylene glycol). Specific examples of such esters includesdibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctylsebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate,didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester oflinoleic acid dimer, and the complex ester formed by reacting one moleof sebacic acid with two moles of tetraethylene glycol and two moles of2-ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C₅ to C₁₂monocarboxylic acids and polyols and polyol esters such as neopentylglycol, trimethylolpropane, pentaerythritol, dipentaerythritol andtripentaerythritol.

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- orpolyaryloxysilicone oils and silicate oils comprise another useful classof synthetic lubricants; such oils include tetraethyl silicate,tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate,tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl)silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane, poly(methyl)siloxanesand poly(methylphenyl)siloxanes. Other synthetic lubricating oilsinclude liquid esters of phosphorous-containing acids (e.g., tricresylphosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid)and polymeric tetrahydrofurans.

Other examples of base oil are gas-to-liquid (“GTL”) base oils, i.e. thebase oil may be oil derived from Fischer-Tropsch-synthesizedhydrocarbons made from synthesis gas containing hydrogen and carbonmonoxide using a Fischer-Tropsch catalyst. These hydrocarbons typicallyrequire further processing in order to be useful as base oil. Forexample, they may, by methods known in the art, be hydroisomerized;hydrocracked and hydroisomerized; dewaxed; or hydroisomerized anddewaxed.

The oil of lubricating viscosity may comprise a Group I, Group II orGroup III, base stock or base oil blends of the aforementioned basestocks. Preferably, the oil of lubricating viscosity is a Group II orGroup III base stock, or a mixture thereof, or a mixture of a Group Ibase stock and one or more a Group II and Group III. Preferably, a majoramount of the oil of lubricating viscosity is a Group II, Group m, GroupIV or Group V base stock, or a mixture thereof. In one particularembodiment, it is preferred that greater than 50 mass %, such as greaterthan 60 mass % of the oil of lubricating viscosity is mineral oil. Thebase stock, or base stock blend preferably has a saturate content of atleast 65%, more preferably at least 75%, such as at least 85%. Mostpreferably, the base stock, or base stock blend, has a saturate contentof greater than 90%. Preferably, the oil or oil blend will have a sulfurcontent of no greater than 0.5 mass % (e.g., from about 0.001 to about0.5 mass %), such as no greater than 0.1 mass % (e.g., from about 0.001to about 0.1 mass %), preferably from about 0.005 to about 0.05 mass %.

Preferably the volatility of the oil or oil blend, as measured by theNoack volatility test (ASTM D5880), is less than or equal to 30 mass %,preferably less than or equal to 25 mass %, more preferably less than orequal to 20 mass %, most preferably less than or equal to 16 mass %.Preferably, the viscosity index (VI) of the oil or oil blend is at least85, preferably at least 100, most preferably from about 105 to 140.

Definitions for the base stocks and base oils in this invention are thesame as those found in the American Petroleum Institute (API)publication “Engine Oil Licensing and Certification System”, IndustryServices Department, Fourteenth Edition, December 1996, Addendum 1,December 1998. Said publication categorizes base stocks as follows:

-   -   a) Group I base stocks contain less than 90 percent saturates        and/or greater than 0.03 percent sulfur and have a viscosity        index greater than or equal to 80 and less than 120 using the        test methods specified in Table I.    -   b) Group II base stocks contain greater than or equal to 90        percent saturates and less than or equal to 0.03 percent sulfur        and have a viscosity index greater than or equal to 80 and less        than 120 using the test methods specified in Table I.    -   c) Group II base stocks contain greater than or equal to 90        percent saturates and less than or equal to 0.03 percent sulfur        and have a viscosity index greater than or equal to 120 using        the test methods specified in Table I.    -   d) Group IV base stocks are polyalphaolefins (PAO).

e) Group V base stocks include all other base stocks not included inGroup I, II, III, or IV. TABLE I Analytical Methods for Base StockProperty Test Method Saturates ASTM D 2007 Viscosity Index ASTM D 2270Sulfur ASTM D 2622 ASTM D 4294 ASTM D 4927 ASTM D 3120

The non-hydrogenated olefm (co)polymer useful in the practice of thepresent invention is preferably a polymer or copolymer of one or moreacyclic olefin monomers. Generally, the non-hydrogenated olefin(co)polymers useful in the invention have, or have on average, about onedouble bond per polymer chain.

The (co)polymer may be prepared by polymerizing alpha-olefin monomer, ormixtures of alpha-olefin monomers, or mixtures comprising ethylene andat least one C₃ to C₂₈ alpha-olefin monomer, in the presence of acatalyst system comprising at least one metallocene (e.g., acyclopentadienyl-transition metal compound) and an alumoxane compound.Using this process, a polymer in which 95% or more of the polymer chainspossess terminal ethenylidene-type unsaturation can be provided. Thepercentage of polymer chains exhibiting terminal ethenylideneunsaturation may be determined by FTIR spectroscopic analysis,titration, or C¹³ NMR. Interpolymers of this latter type may becharacterized by the formula POLY-C(R¹)═CH₂ wherein R¹ is C₁ to C₂₆alkyl, preferably C₁ to C₁₈ alkyl, more preferably C₁ to C₈ alkyl, andmost preferably C₁ to C₂ alkyl, (e.g., methyl or ethyl) and wherein POLYrepresents the polymer chain. The chain length of the R¹ alkyl groupwill vary depending on the comonomer(s) selected for use in thepolymerization. A minor amount of the polymer chains can containterminal ethenyl, i.e. vinyl, unsaturation, i.e. POLY-CH═CH₂, and aportion of the polymers can contain internal monounsaturation, e.g.,POLY-CH═CH(R¹), wherein R¹ is as defined above. These terminallyunsaturated interpolymers may be prepared by known metallocene chemistryand may also be prepared as described in U.S. Pat. Nos. 5,498,809;5,663,130; 5,705,577; 5,814,715; 6,022,929 and 6,030,930.

Another useful class of (co)polymers is (co)polymers prepared bycationic polymerization of isobutene, styrene, and the like. Common(co)polymers from this class include polyisobutenes obtained bypolymerization of a C₄ refinery stream having a butene content of about35 to about 75% by wt., and an isobutene content of about 30 to about60% by wt., in the presence of a Lewis acid catalyst, such as aluminumtrichloride or boron trifluoride, with aluminium trichloride preferred.A preferred source of monomer for making poly-n-butenes is petroleumfeedstreams such as Raffinate II. These feedstocks are disclosed in theart such as in U.S. Pat. No. 4,952,739. Polyisobutylene is a mostpreferred polymer of the present invention because it is readilyavailable by cationic polymerization from butene streams (e.g., usingAlCl₃ or BF₃ catalysts). Such polyisobutylenes generally containresidual unsaturation in amounts of about one ethylenic double bond perpolymer chain, positioned along the chain. A preferred embodimentutilizes polyisobutylene prepared from a pure isobutylene stream or aRaffinate I stream to prepare reactive isobutylene polymers withterminal vinylidene olefins. Preferably, these polymers, referred to ashighly reactive polyisobutylene (HR-PIB), have a terminal vinylidenecontent of at least 65%, e.g., 70%, more preferably at least 80%, mostpreferably, at least 85%. The preparation of such polymers is described,for example, in U.S. Pat. No. 4,152,499. HR-PIB is known and HR-PIB iscommercially available under the tradenames Glissopal™ (from BASF) andUltravis™ (from BP-Amoco).

In another embodiment, the non-hydrogenated olefin (co)polymer, forexample, polyisobutylene, has at most 10, such as 5 to 10, %, of thepolymer chains possessing a terminal double bond (or terminalethenylidene-type or terminal vinylidene unsaturation). Such a polymeris considered not highly reactive, an example of a commerciallyavailable polymer is under tradename Napvis™ (from BP-Amoco), andusually obtained by polymerization with aluminium trichloride ascatalyst.

Preferably the (co)polymer is derived from polymerisation of one or moreolefins having 2 to 10, such as 3 to 8, carbon atoms. An especiallypreferred olefin is butene, advantageously isobutene.

The number average molecular weight of the non-hydrogenated olefin(co)polymer useful in the present invention is preferably in the rangeof from about 450 to about 2300, such as from about 450 to about 1300,preferably from about 450 to about 950. The molecular weight can bedetermined by several known techniques. A convenient method for suchdetermination is by gel permeation chromatography (GPC), whichadditionally provides molecular weight distribution information (see W.W. Yau, J. J Kirkland and D. D Bly, “Modern Size Exclusion LiquidChromatography”, John Wiley and Sons, New York, 1979). Further, it ispreferred that the kinematic viscosity of the non-hydrogenated olefinpolymer at 100° C. as measured according to ASTM D445, is at least 9 or15, such as 100 or 150 to 3000, advantageously 200 to 2500 or 2700mm²s⁻¹. In one embodiment of the present invention, a polyisobutylenepolymer having a number average molecular weight of 450 to 2300, and akinematic viscosity at 100° C. of from about 200 to 2400 mm²s⁻¹ wasfound to provide particularly beneficial properties. Lubricating oilcompositions of the present invention can contain the non-hydrogenatedolefin polymer in an amount of from about 0.2 to about 10.0 mass %, suchas from about 0.3 to about 5.0 mass %, particularly from about 0.5 toabout 3.0 mass %, preferably from about 1.0 to about 2.5 mass %.

Dispersants (or dispersant additives), such as ashless (i.e. metal-free)dispersants hold solid and liquid contaminants, resulting from oxidationduring use, in suspension and thus preventing sludge flocculation andprecipitation or deposition on metal parts; they comprise long-chainhydrocarbons, to confer oil-solubility, with a polar head capable ofassociating with particles to be dispersed. A noteworthy group ishydrocarbon-substituted succinimides.

Generally, ashless dispersants form substantially no ash on combustion,in contrast to metal-containing (and thus ash-forming) detergents.Borated, metal-free dispersants are also regarded herein as ashlessdispersants. “Substantially no ash” means that the dispersant may givetrace amounts of ash on combustion, but amounts which do not havepractical or significant effect on the performance of the dispersant. Adispersant additive composition containing two or more dispersants mayalso be used.

Ashless, dispersants comprise an oil soluble polymeric long chainbackbone having functional groups capable of associating with particlesto be dispersed. Typically, such dispersants have amine, amine-alcoholor amide polar moieties attached to the polymer backbone, often via abridging group. The ashless dispersant may be, for example, selectedfrom oil soluble salts, esters, amino-esters, amides, imides andoxazolines of long chain hydrocarbon-substituted mono- andpolycarboxylic acids or anhydrides thereof; thiocarboxylate derivativesof long chain hydrocarbons; long chain aliphatic hydrocarbons havingpolyamine moieties attached directly thereto; and Mannich condensationproducts formed by condensing a long chain substituted phenol withformaldehyde and polyalkylene polyamine. Suitable dispersants include,for example, derivatives of long chain hydrocarbyl-substitutedcarboxylic acids, in which the hydrocarbyl group has a number averagemolecular weight tends of less than 15,000, such as less than 5,000;examples of such derivatives being derivatives of high molecular weighthydrocarbyl-substituted succinic acid. Such hydrocarbyl-substitutedcarboxylic acids may be derivatized with, for example, anitrogen-containing compound, advantageously a polyalkylene polyamine oramine-alcohol or amide or ester. Particularly preferred dispersants arethe reaction products of polyalkylene amines with alkenyl succinicanhydrides. Examples of specifications disclosing dispersants of thelast-mentioned type are U.S. Pat. Nos. 3,202,678; 3,154,560; 3,172,892;3,024,195; 3,024,237; 3,219,666; 3,216,936; and BE-A-662 875.

The dispersant(s) are preferably non-polymeric (e.g., are mono- orbis-succinimides). The dispersant(s) of the present invention mayoptionally be borated. Such dispersants can be borated by conventionalmeans, as generally taught in U.S. Pat. Nos. 3,087,936, 3,254,025 and5,430,105. Boration of the dispersant is readily accomplished bytreating an acyl nitrogen-containing dispersant with a boron compoundsuch as boron oxide, boron halide boron acids, and esters of boronacids, in an amount sufficient to provide from about 0.1 to about 20atomic proportions of boron for each mole of acylated nitrogencomposition. Combinations of borated and non-borated dispersants mayalso be employed.

An ashless succinimide or a derivative thereof, obtainable from apolyisobutenylsuccinic anhydride produced from polybutene and maleicanhydride by a thermal reaction method using neither chlorine nor achlorine atom-containing compound, is a preferred dispersant.

Dispersancy may be provided by polymeric compounds capable of providingviscosity index improving properties and dispersancy, such compounds areknown as a dispersant viscosity index improver additive or amultifunctional viscosity index improver. Such polymers differ fromconventional viscosity index improvers in that they provide performanceproperties, such as dispersancy and/or antioxidancy, in addition toviscosity index improvement (see below under viscosity modifiers forfurther detail on multifunctional viscosity modifiers). In the event, adispersant viscosity index improver additive is used in the lubricatingoil compositions of the present invention, a dispersant additive is,preferably, also present.

Typically, one or more dispersants and/or dispersant viscosity indeximprovers, are used in heavy duty diesel (HDD) engine lubricating oilcomposition in amounts that provide the lubricating oil composition witha nitrogen content of from about 0.08 mass % to about 0.35 mass %, suchas from about 0.09 mass % to about 0.25 mass %, preferably from about0.10 mass % to about 0.20 mass %. In a passenger car diesel enginelubricating oil composition (PCDO), dispersant is generally added inamounts that provide the lubricating oil composition with a nitrogencontent of from about 0.04 mass % to about 0.10 mass %, such as fromabout 0.05 mass % to about 0.09 mass %, preferably from about 0.065 mass% to about 0.085 mass %. In a passenger car motor oil for aspark-ignited engine (PCMO), dispersant is generally added in amountsthat provide the lubricating oil composition with a nitrogen of fromabout 0.02 mass % to about 0.12 mass %, such as from about 0.03 mass %to about 0.08 mass %, preferably from about 0.035 mass % to about 0.05mass %. In manual transmission fluids (MTF), dispersant is generallyadded in amounts that provide the lubricating oil composition with anitrogen content of from about 0.02 mass % to about 0.08 mass %, such asfrom about 0.025 mass % to about 0.06 mass %, preferably from about 0.03mass % to about 0.05 mass %. In an automatic transmission fluid (ATF),dispersant is generally added in an amount providing the lubricating oilcomposition with a nitrogen content of from about 0.02 mass % to about0.14 mass %, such as from about 0.05 mass % to about 0.11 mass %,preferably from about 0.06 mass % to about 0.08 mass %.

A detergent (or detergent additive) reduces formation of pistondeposits, for example high-temperature varnish and lacquer deposits, bykeeping finely divided solids in suspension in engines; it may also haveacid-neutralizing properties. A detergent comprises metal salts oforganic acids, which are referred herein as soaps or surfactants. Adetergent has a polar head, i.e. the metal salt of the organic acid,with a long hydrophobic tail for oil solubility. Therefore, the organicacids typically have one or more functional groups, such as OH or COOHor SO₃H, for reacting with a metal, and a hydrocarbyl substituent. Adetergent may be overbased, in which case the detergent contains anexcess of metal in relation to the stoichiometric quantity needed forthe neutralization of the organic acid. This excess is in the form of acolloidal dispersion, typically metal carbonate and/or hydroxide, withthe metal salts of organic acids in a micellar structure.

Examples of organic acids include sulfonic acids, phenols and sulfurizedderivatives thereof, and carboxylic acids including aromatic carboxylicacids.

Phenols may be non-sulfurized or sulfurized. Further, the term “phenol”as used herein includes phenols containing more than one hydroxyl group(for example, alkyl catechols) or fused aromatic rings (for example,alkyl naphthols) and phenols which have been modified by chemicalreaction, for example, alkylene-bridged phenols and Mannichbase-condensed phenols; and saligenin-type phenols (produced by thereaction of a phenol and an aldehyde under basic conditions). Thephenols are frequently used in sulfurized form. Details of sulfurizationprocesses are known to those skilled in the art, for example, see U.S.Pat. Nos.4,228,022 and 4,309,293.

As indicated above, the term “phenol” as used herein includes phenolswhich have been modified by chemical reaction with, for example, analdehyde, and Mannich base-condensed phenols. Aldehydes with whichphenols may be modified include, for example, formaldehyde,propionaldehyde and butyraldehyde. The preferred aldehyde isformaldehyde. Aldehyde-modified phenols suitable for use in accordancewith, the present invention are described in, for example, U.S. Pat.Nos. 5,259,967 and 6,310,009. Mannich base-condensed phenols areprepared by the reaction of a phenol, an aldehyde and an amine. Examplesof suitable Mannich base-condensed phenols are described in U.S. Pat.Nos. 4,708,809 and 4,740,321. In general, the phenols may includesubstituents other than those mentioned above. Examples of suchsubstituents are methoxy groups and halogen atoms.

Sulfonic acids are typically obtained by sulfonation ofhydrocarbyl-substituted, especially alkyl-substituted, aromatichydrocarbons, for example, those obtained from the fractionation ofpetroleum by distillation and/or extraction, or by the alkylation ofaromatic hydrocarbons. The alkylaryl sulfonic acids usually contain fromabout 22 to about 100 or more carbon atoms. The sulfonic acids may besubstituted by more than one alkyl group on the aromatic moiety, forexample they may be dialkylaryl sulfonic acids. Preferably the sulfonicacid has a number average molecular weight of 350 or greater, morepreferably 400 or greater, especially 500 or greater, such as 600 orgreater. Number average molecular weight may be determined by ASTMD3712. Another type of sulfonic acid which may be used in accordancewith the invention comprises alkyl phenol sulfonic acids. Such sulfonicacids can be sulfurized.

Carboxylic acids include mono and dicarboxylic acids. Preferredmonocarboxylic acids are those containing 8 to 30, especially 8 to 24,carbon atoms. (Where this specification indicates the number of carbonatoms in a carboxylic acid, the carbon atom(s) in the carboxylicgroup(s) is/are included in that number). Examples of monocarboxylicacids are iso-octanoic acid, stearic acid, oleic acid, palmitic acid andbehenic acid. Iso-octanoic acid may, if desired, be used in the form ofthe mixture of C8 acid isomers sold by Exxon Chemical under the tradename “Cekanoic”. Other suitable acids are those with tertiarysubstitution at the α-carbon atom and dicarboxylic acids with 2 or morecarbon atoms separating the carboxylic groups. Further, dicarboxylicacids with more than 35 carbon atoms, for example, 36 to 100 carbonatoms, are also suitable. Unsaturated carboxylic acids can besulfurized.

A preferred type of carboxylic acid is an aromatic carboxylic acid. Thearomatic moiety of the aromatic carboxylic acid can contain heteroatoms, such as nitrogen and oxygen. Preferably, the moiety contains onlycarbon atoms; more preferably the moiety contains six or more carbonatoms; for example benzene is a preferred moiety. The aromaticcarboxylic acid may contain one or more aromatic moieties, such as oneor more benzene rings, either fused or connected via alkylene bridges.

The carboxylic moiety may be attached directly or indirectly to thearomatic moiety. Preferably the carboxylic acid group is attacheddirectly to a carbon atom on the aromatic moiety, such as a carbon atomon the benzene ring. The aromatic moiety may also contain a secondfunctional group, such as a hydroxyl group or a sulfonate group, whichcan be attached directly or indirectly to a carbon atom on the aromaticmoiety. Preferred examples of aromatic carboxylic acids are salicylicacids and sulfurized derivatives thereof, such as hydrocarbylsubstituted salicylic acid and derivatives thereof. Processes forsulfurizing, for example a hydrocarbyl-substituted salicylic acid, areknown to those skilled in the art.

Salicylic acids are typically prepared by carboxylation, for example, bythe Kolbe-Schmitt process, of phenoxides, and in that case, willgenerally be obtained, normally in a diluent, in admixture withuncarboxylated phenol.

Preferred substituents for oil-soluble salicylic acids are alkylsubstituents. In alkyl-substituted salicylic acids, the alkyl groupsadvantageously contain 5 to 100, preferably 9 to 30, especially 14 to20, carbon atoms. Where there is more than one alkyl group, the averagenumber of carbon atoms in all of the alkyl groups is preferably at least9 to ensure adequate oil-solubility.

The metal detergent may be neutral or overbased, such terms are known inthe art. A detergent additive composition may comprise one or moredetergent additives, which can be a neutral detergent, an overbaseddetergent or a mixture of both. The Total Base Number (TBN) ofdetergents will conventionally range from 15 to 600.

Detergents generally useful in the formulation of lubricating oilcompositions also include “hybrid” detergents formed with mixedsurfactant systems, e.g., phenate/salicylates (sometimes referred to as“phenalates”), sulfonate/phenates, sulfonate/salicylates,sulfonates/phenates/salicylates, as described, for example, in U.S. Pat.Nos. 6,153,565; 6,281,179; 6,429,178; and 6,429,179.

A detergent additive composition may contain two or more detergents, forexample, an alkali metal, such as sodium, detergent, and an alkalineearth metal, such as calcium and/or magnesium, detergent. The detergentadditive composition may also comprise an ashless detergent, i.e. anon-metal containing detergent, typically in the form of an organic saltof an organic acid. The detergents are preferably metal containing andGroup 1 and Group 2 metals are preferred as metals in the detergents,more preferably calcium and magnesium, especially calcium.

Typically, one or more detergents are used in heavy duty diesel (HDD)engine lubricating oil composition in amounts that provide thelubricating oil composition with a TBN of from about 4.0 to about 11.5,such as from about 6.0 to about 9.5, preferably from about 7.0 to about8.25. In a passenger car diesel engine lubricating oil composition(PCDO), detergent is generally added in amounts that provide thelubricating oil composition with a TBN of from about 5.0 to about 12.0,such as from about 6.0 to about 11.0, preferably from about 7.0 to about10.5. In a passenger car motor oil for a spark-ignited engine (PCMO),detergent(s) is generally added in amounts that provide the lubricatingoil composition with a TBN of from about 2.5 to about 9.9, such as fromabout 4.0 to about 8.0, preferably from about 4.5 to about 7.25. In apower transmission fluid (PTF), detergent(s) is generally added inamounts that provide the lubricating oil composition with a TBN of fromabout 0.0 to about 10.0, such as from about 0.5 to about 5.0, preferablyfrom about 1.0 to about 2.5. Where the detergent is a sulfonatedetergent, a sulfurized phenate detergent, or a hybrid detergentcontaining a sulfurized phenate and/or sulfonate component, the use of aconventional amount of such detergents can introduce into thelubricating oil composition as much as 0.04 mass %, even as much as 0.15mass %, such as from about 0.06 to about 0.12 mass % of sulfur.

In one embodiment, the invention is directed specifically to lubricatingoil compositions containing salicylate detergent in an amountintroducing at least about 9 mmols (e.g, about 12 to about 50 mmols),such as at least about 18 mmols (e.g. about 18 to about 33 mmols)particularly at least about 24 mmols of salicylate soap per kilogram offinished lubricant and from about 1.0 mass % to about 2.5 mass % of thenon-hydrogenated polymer described supra.

In another embodiment, the invention is directed specifically to low ashcompositions having an ash (reported as sulfated ash or SASH) content ofless than 1.1 mass %, such as less than 1.05 mass%, preferably less than0.8 mass %; and a sulfur content of from about 0.10 mass % to about 0.40mass %, such as from about 0.15 mass % to about 0.35 mass %, preferablyfrom about 0.20 mass % to about 0.30 mass % of sulfur, whichcompositions contain salicylate detergent in an amount introducing atleast about 9 mmols, such as at least about 18 mmols, preferably atleast about 24 mmols, of salicylate soap per kilogram of finishedlubricant and from about 1.0 mass % to about 2.5 mass % of thenon-hydrogenated polymer described supra.

Anti-wear agents reduce friction and excessive wear and are usuallybased on compounds containing sulfur or phosphorus or both.Dihydrocarbyl dithiophosphate metal salts are frequently used asanti-wear and antioxidant agents. The metal may be an alkali or alkalineearth metal, or aluminum, lead, tin, molybdenum, manganese, nickel orcopper. The zinc salts (ZDDP) are most commonly used in lubricating oilin amounts of 0.1 to 10, preferably 0.2 to 2 mass %, based upon thetotal weight of the lubricating oil composition. They may be prepared inaccordance with known techniques by first forming a dihydrocarbyldithiophosphoric acid (DDPA), usually by reaction of one or more alcoholor a phenol with P₂S₅ and then neutralizing the formed DDPA with a zinccompound. For example, a dithiophosphoric acid may be made by reactingmixtures of primary and secondary alcohols having 1 to 18, preferably 2to 12, carbon atoms. Alternatively, multiple dithiophosphoric acids canbe prepared where the hydrocarbyl groups on one are entirely secondaryin character and the hydrocarbyl groups on the others are entirelyprimary in character. To make the zinc salt any basic or neutral zinccompound could be used but the oxides, hydroxides and carbonates aremost generally employed. Commercial additives frequently contain anexcess of zinc due to use of an excess of the basic zinc compound in theneutralization reaction.

ZDDP provides excellent wear protection at a comparatively low cost andalso functions as an antioxidant. Preferably a zinc dialkyldithiophosphate composition comprising one or more zinc dialkyldithiophosphate, which composition especially contains a mixture ofprimary and secondary alkyl groups, wherein the secondary alkyl groupsare in a major molar proportion, such as at least 60, advantageously atleast 75, more especially at least 85, mole %, based on the amount ofalkyl groups, is useful in the present invention. Preferably a zincdithiophosphate composition has 90 mole % secondary alkyl groups and 10mole % primary alkyl groups.

When used in conventional amounts, sulfur-containing antiwear agents canintroduce into the lubricating oil composition as much as 0.15 mass %,and even as much as 0.30 mass %, such as from about 0.16 to about 0.25mass % of sulfur.

Anti-oxidants increase the composition's resistance to oxidation and maywork by combining with and modifying peroxides to render them harmlessby decomposing peroxides or by rendering an oxidation catalyst inert.They may be classified as radical scavengers (e.g. sterically hinderedphenols, secondary aromatic amines, and organo-copper salts);hydroperoxide decomposers (e.g. organo-sulfur and organophosphorusadditives); and multifunctionals. Such anti-oxidants (or oxidationinhibitors) include hindered phenols, aromatic amine compounds, alkalineearth metal and metal-free alkylphenolthioesters having preferably C₅ toC₁₂ alkyl side chains, ashless alkylene bridged phenols,phosphosulfurized and sulftrized hydrocarbons, phosphorous esters, metaland metal-free thiocarbamates & derivatives thereof, oil soluble coppercompound as described in U.S. Pat. No. 4,867,890, and molybdenumcontaining compounds. In the practice of the present invention, the useor otherwise of certain anti-oxidants may confer certain benefits. Forexample, in one embodiment it is preferred that an anti-oxidantcomposition comprising a hindered phenol with an ester group is used. Inanother embodiment, it is preferred to employ an anti-oxidantcomposition comprising a secondary aromatic amine and said hinderedphenol. Preferably an antioxidant composition comprising an aromaticamine, such as diphenylamine and/or a hindered phenol compound, such as3,5-bis(alkyl)4-hydroxyphenyl carboxylic acid esters, e.g. IRGANOX® L135as sold by Ciba Specialty Chemicals, is useful.

Friction modifiers include boundary additives that lower frictioncoefficients and hence improve fuel economy. Examples are esters ofpolyhydric alcohols such as glycerol monoesters of higher fatty acids,for example glycerol mono-oleate; esters of long chain polycarboxylicacids with diols, for example the butane diol esters of dimerizedunsaturated fatty acids; oxazoline compounds; and alkoxylatedalkyl-substituted mono-amines, and alkyl ether amines, for example,ethoxylated tallow amine and ethoxylated tallow ether amine.Molybdenum-containing compounds and ashless dithiocarbamates are alsoexamples of known friction modifiers. Conventionally, one or moreorganic friction modifiers are used in an amount of 0.1 to 0.5, such as0.2 to 0.4, mass %, based on the mass of the oil composition.

The molybdenum-containing compounds, preferably molybdenum-sulfurcompounds, useful in the present invention may be mononuclear orpolynuclear. In the event that the compound is polynuclear, the compoundcontains a molybdenum core consisting of non-metallic atoms, such assulfur, oxygen and selenium, preferably consisting essentially ofsulfur.

To enable the molybdenum-sulfur compound to be oil-soluble oroil-dispersible, one or more ligands are bonded to a molybdenum atom inthe compound. The bonding of the ligands includes bonding byelectrostatic interaction as in the case of a counter-ion and forms ofbonding intermediate between covalent and electrostatic bonding. Ligandswithin the same compound may be differently bonded. For example, aligand may be covalently bonded and another ligand may beelectrostatically bonded.

Preferably, the or each ligand is monoanionic and examples of suchligands are dithiophosphates, dithiocarbamates, xanthates, carboxylates,thioxanthates, phosphates and hydrocarbyl, preferably alkyl, derivativesthereof. Preferably, the ratio of the number of molybdenum atoms, forexample, in the core in the event that the molybdenum-sulfur compound isa polynuclear compound, to the number of monoanionic ligands, capable ofrendering the compound oil-soluble or oil-dispersible, is greater than 1to 1, such as at least 3 to 2.

The molybdenum-sulfur compound's oil-solubility or oil-dispersibilitymay be influenced by the total number of carbon atoms present among allof the compound's ligands. The total number of carbon atoms presentamong all of the hydrocarbyl groups of the compound's ligands typicallywill be at least 21, e.g., 21 to 800, such as at least 25, at least 30or at least 35. For example, the number of carbon atoms in each alkylgroup will generally range between 1 and 100, preferably 1 and 40, andmore preferably between 3 and 20. Examples of molybdenum-sulfurcompounds include dinuclear molybdenum-sulfur compounds and trinuclearmolybdenum-sulfur compounds.

An example of a dinuclear molybdenum-sulfur compound is represented bythe formula:

where R₁ to R₄ independently denote a straight chain, branched chain oraromatic hydrocarbyl group having 1 to 24 carbon atoms; and X₁ to X₄independently denote an oxygen atom or a sulfur atom. The fourhydrocarbyl groups, R₁ to R₄, may be identical or different from oneanother.

In a preferred embodiment, the molybdenum-sulfur compound is anoil-soluble or oil-dispersible trinuclear molybdenum-sulfur compound.Examples of trinuclear molybdenum-sulfur compounds are disclosed in U.S.Pat. Nos. 5,888,945; 5,906,968; 6,010,987; 6,110,878; 6,153,564;6,232,276; 6,358,894; 6,541,429; 6,569,820; and European patentapplication no. 02078011, each of which are incorporated into thepresent description by reference, particularly with respect to thecharacteristics of the molybdenum compound or additive disclosedtherein.

Preferably, the trinuclear molybdenum-sulfur compounds are representedby the formula Mo₃S_(k)E_(x)L_(n)A_(p)Q_(z), wherein k is an integer ofat least 1; E represents a non-metallic atom selected from oxygen andselenium; x can be 0 or an integer, and preferably k+x is at least 4,more preferably in the range of 4 to 10, such as 4 to 7, most preferably4 or 7; L represents a ligand that confers oil-solubility oroil-dispersibility on the molybdenum-sulfur compound, preferably L is amonoanionic ligand; n is an integer in the range of 1 to 4; A representsan anion other than L, if L is an anionic ligand; p can be 0 or aninteger; Q represents a neutral electron-donating compound; and z is inthe range of 0 to 5 and includes non-stoichiometric values.

Those skilled in the art will realize that formation of the trinuclearmolybdenum-sulfur compound will require selection of appropriate ligands(L) and other anions (A), depending on, for example, the number ofsulfur and E atoms present in the core, i.e. the total anionic chargecontributed by sulfur atom(s), E atom(s), if present, L and A, ifpresent, must be −12. The trinuclear molybdenum-sulfur compound may alsohave a cation other than molybdenum, for example, (alkyl)ammonium, amineor sodium, if the anionic charge exceeds −12.

Examples of Q include water, alcohol, amine, ether and phosphine. It isbelieved that the electron-donating compound, Q, is merely present tofill any vacant coordination sites on the trinuclear molybdenum-sulfurcompound. Examples of A can be of any valence, for example, monovalentand divalent and include disulfide, hydroxide, alkoxide, amide andthiocyanate or derivative thereof; preferably A represents a disulfideion. Preferably, L is monoanionic ligand, such as dithiophosphates,dithiocarbamates, xanthates, carboxylates, thioxanthates, phosphates andhydrocarbyl, preferably alkyl, derivatives thereof. When n is 2 or more,the ligands can be the same or different. In an embodiment,independently of the other embodiments, k is 4 or 7, n is either 1 or 2,L is a monoanionic ligand, p is an integer to confer electricalneutrality on the compound based on the anionic charge on A and each ofx and z is 0. In a further embodiment, independently of the otherembodiments, k is 4 or 7, L is a monoanionic ligand, n is 4 and each ofp, x and z is 0. Other examples of molybdenum containing compoundsinclude molybdenum carboxylates and molybdenum nitrogen complexes, bothof which may be sulfurised.

Where a sulfur-containing molybdenum compound is employed as a frictionmodifier and/or antioxidant, and used in a conventional amount such asan amount providing from about 20 ppm to about 250 ppm, such as fromabout 50 ppm to about 125ppm of Mo, such compounds can introduce intothe lubricating oil composition about 0.004 mass % or more, or about0.008 mass % or more, such as from about 0.004 mass % to about 0.090mass %, e.g., from about 0.008 to about 0.025 mass % of sulfur.

Boron may also be present in the lubricating oil compositions of thepresent invention. Boron-containing additives may be prepared byreacting a boron compound with an oil-soluble or oil-dispersibleadditive or compound. Boron compounds include boron oxide, boron oxidehydrate, boron trioxide, boron trifluoride, boron tribromide, borontrichloride, boron acid such as boronic acid, boric acid, tetraboricacid and metaboric acid, boron hydrides, boron amides and various estersof boron acids. Examples of boron-containing additives include a borateddispersant; a borated dispersant VI improver; an alkali metal or a mixedalkali metal or an alkaline earth metal borate; a borated overbasedmetal detergent; a borated epoxide; a borate ester; a sulfurized borateester; and a borate amide. A preferred boron-containing additive is aborated dispersant.

Examples of other additives include rust inhibitors, corrosioninhibitors, pour point depressants, anti-foaming agents and viscositymodifiers.

Rust inhibitors selected from the group consisting of nonionicpolyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols, andanionic alkyl sulfonic acids may be used.

Copper and lead bearing corrosion inhibitors may be used, but aretypically not required with the formulation of the present invention.Typically such compounds are the thiadiazole polysulfides containingfrom 5 to 50 carbon atoms, their derivatives and polymers thereof.Derivatives of 1,3,4-thiadiazoles, such as those described in U.S. Pat.Nos. 2,719,125; 2,719,126; and 3,087,932; are typical. Other similarmaterials are described in U.S. Pat. Nos. 3,821,236; 3,904,537;4,097,387; 4,107,059; 4,136,043; 4,188,299; and 4,193,882. Otheradditives are the thio and polythio sulfenamides of thiadiazoles such asthose described in U.K. Patent Specification No. 1,560,830.Benzotriazoles derivatives also fall within this class of additives.When these compounds are included in the lubricating composition, theyare preferably present in an amount not exceeding 0.2 mass % (A.I.).

A small amount of a demulsifying component may be used. A preferreddemulsifying component is described in EP 330,522. It is obtained byreacting an alkylene oxide with an adduct obtained by reacting abis-epoxide with a polyhydric alcohol. The demulsifier should be used ata level not exceeding 0.1 mass % A.I. A treat rate of 0.001 to 0.05 mass% (A.I.) is convenient.

Pour point depressants, otherwise known as lube oil improvers, lower theminimum temperature at which the fluid will flow or can be poured. Suchadditives are well known. Typical of those additives which improve thelow temperature fluidity of the fluid are C₈ and C₁₈ dialkylfumarate/vinyl acetate copolymers, polyalkylmethacrylates and the like.

Foam control can be provided by many compounds including an antifoamantof the polysiloxane type, for example, silicone oil or polydimethylsiloxane.

Viscosity index improvers (or viscosity modifiers) impart high and lowtemperature operability to a lubricating oil and permit it to remainshear stable at elevated temperatures and also exhibit acceptableviscosity or fluidity at low temperatures. Suitable compounds for use asviscosity modifiers are generally high molecular weight hydrocarbonpolymers, e.g. polyisobutylene, copolymers of ethylene and propylene andhigher alpha-olefins; polyesters, such as polymethacrylates;hydrogenated poly(styrene-co-butadiene or -isoprene) polymers andmodifications (e.g., star polymers); and esterifiedpoly(styrene-co-maleic anhydride) polymers . Oil-soluble viscositymodifying polymers generally have number average molecular weights of atleast 15,000 to 1,000,000, preferably 20,000 to 600,000, as determinedby gel permeation chromatography or light scattering methods. Thedisclosure in Chapter 5 of “Chemistry & Technology of Lubricants”,edited by R. M. Mortier and S. T. Orzulik, First edition, 1992. BlackieAcademic & Professional, is incorporated herein. The VM used may havethat sole function, or may be multifunctional, such as demonstratingviscosity index improving properties as well as dispersant properties.Dispersant olefin copolymers and dispersant polymethacrylates areexamples of dispersant viscosity index improver additives. Dispersantviscosity index improver additives are prepared by chemically attachingvarious functional moieties, for example amines, alcohols and amides,onto polymers, which polymers preferably tend to have a number averagemolecular weight of at least 15,000, such in the range from 20,000 to600,000, as determined by gel permeation chromatography or lightscattering methods. The polymers used may be those described below withrespect to viscosity modifiers. Therefore, amine molecules may beincorporated to impart dispersancy and/or antioxidancy characteristics,whereas phenolic molecules may be incorporated to improve antioxidantproperties. A specific example, therefore, is an inter-polymer ofethylene-propylene post grafted with an active monomer such as maleicanhydride and then derivatized with, for example, an alcohol or amine.In the event a dispersant viscosity modifier is used in the presentinvention, the nitrogen content of the lubricating oil composition alsoincludes that derived from the dispersant viscosity modifier. An exampleof a dispersant viscosity modifier is Hitec® 5777, which is manufacturedand sold by Afton Corp. U.S. Pat. Nos.4,867,890 and 5,958,848 describeexamples of dispersant viscosity index improvers, which are accordinglyincorporated herein. Generally, viscosity modifiers, whethermultifunctional or not, are used in an amount depending on the desiredviscometric grade (e.g., SAE 10W-40) of the lubricating oil composition,for example, an amount of 0.001 to 2, preferably 0.01 to 1.5, such as0.1 to 1, mass % of the polymer, based on the mass of the oilcomposition.

Representative effective amounts of such additives, when used inlubricating oil compositions, are as follows: Mass % a.i.* Mass % a.i.*Additive (Broad) (Preferred) Viscosity Modifier  0.01-6  0.01-4Corrosion Inhibitor  0.0-5  0.01-1.5 Oxidation Inhibitor  0.01-5  0.01-3Friction Reducer  0.01-5  0.01-1.5 Dispersant  0.1-20  0.1-8Multifunctional Viscosity Modifier  0.0-5  0.05-5 Detergent  0.01-6 0.01-4 Anti-wear Agent  0.01-6  0.01-4 Pour Point Depressant  0.01-5 0.01-1.5 Rust Inhibitor  0.0-0.5 0.001-0.2 Anti-Foaming Agent 0.001-0.30.001-0.15 Demulsifier  0.0-0.5 0.001-0.2*mass % active ingredient based on the final lubricating oilcomposition.

An additive concentrate constitutes a convenient means of handling twoor more additives before their use, as well as facilitating solution ordispersion of the additives in lubricant compositions. When preparing alubricant composition that contains more than one type of additive(sometimes referred to as “additive components”), each additive may beincorporated separately. In many instances, however, it is convenient toincorporate the additives as an additive concentrate (a so-calledadditive “package” (also referred to as an “adpack”)) comprising two ormore additives).

In the preparation of the lubricant oil compositions, it is commonpractice to introduce additives in the form of additive concentrate(s)containing the additives. When a plurality of additives are employed itmay be desirable, although not essential, to prepare one or moreadditive concentrates (also known as additive packages) comprising theadditives, whereby several additives, with the exception of viscositymodifiers, multifunctional viscosity modifiers and pour pointdepressants, can be added simultaneously to the oil of lubricatingviscosity to form the lubricating oil composition. Dissolution of theadditive concentrate(s) into the lubricating oil may be facilitated bydiluent or solvents and by mixing accompanied with mild heating, butthis is not essential. The additive concentrate(s) will typically beformulated to contain the additive(s) in proper amounts to provide thedesired concentration in the final formulation when the additiveconcentrate(s) is/are combined with a predetermined amount of oil oflubricating viscosity. If required, the viscosity modifiers, ormultifunctional viscosity modifiers, and pour point depressants are thenseparately added to form a lubricating oil composition.

An additive concentrate may contain 1 to 90, such as 10 to 80,preferably 20 to 80, more preferably 40 to 70, mass % based on activeingredient, of the additives, the remainder being an oleaginous carrieror diluent fluid (for example, an oil of lubricating viscosity). Thefinal lubricating oil composition may typically contain 5 to 40 mass %of the additive concentrate(s).

The amount of additives in the final lubricating oil composition isgenerally dependent on the type of the oil composition, for example, aheavy duty diesel engine lubricating oil composition preferably has 7 to25, more preferably 8 to 23, such as 8 to 20, mass % of additives(including any diluent fluid), based on the mass of the oil composition.A passenger car engine lubricating oil composition, for example, agasoline or a diesel engine oil composition, tends to have a loweramount of additives, for example 2 to 16, such as 3 or 4 to 14,preferably 5 to 12, especially 6 to 10, mass % of additives, based onthe mass of the oil composition. The amounts expressed above excludenon-hydrogenated olefin polymer, viscosity modifier and pour pointdepressant additives.

Generally the viscosity of the additive concentrate is higher than thatof the lubricating oil composition. Typically, the kinematic viscosityat 100° C. of the additive concentrate is at least 50, such as in therange 100 to 200, preferably 120 to 180, mm²s⁻¹ (or cSt).

Thus, a method of preparing a lubricating oil composition according tothe present invention can involve admixing an oil of lubricatingviscosity and one or more of additives or additive concentrates thatcomprises two or more of additives and then, admixing other additivecomponents, such as viscosity modifier, and optionally a multifunctionalviscosity modifier and pour point depressant.

Lubricating oil compositions of the present invention may also beprepared by admixing an oil of lubricating viscosity, an additiveconcentrate containing two or more additive components, anon-hydrogenated olefin polymer and a viscosity modifier, and optionallya multifunctional viscosity modifier and pour point depressant.

It is preferred that lubricating oil compositions of the invention aremultigrade oil compositions having a viscometric grade of SAE 10W-X, SAE5W-X and SAE 0W-X, where X represents 20, 30 and 40; the characteristicsof the different grades can be found in the SAE J300 classification.

Fully formulated lubricating oil compositions of the present inventionpreferably have a sulfur content of from about 0.15 mass % to about 1.0mass %, such as from about 0.20 mass % to about 0.35 mass %. Preferably,the Noack volatility of the fully formulated lubricating oil composition(oil of lubricating viscosity plus all additives) will be no greaterthan 13, such as no greater than 12, preferably no greater than 10.Fully formulated lubricating oil compositions of the present inventionpreferably have a phosphorus content of less than about 1500 ppm, suchas from about 500 to 1500 ppm, preferably less than 1250 ppm, such asfrom about 500 to about 1250 ppm, more preferably less than about 1200ppm, such as from about 500 to about 1200 ppm, still more preferablyless than about 850 ppm, such as from about 500 to 850 ppm, based on thetotal mass of the lubricating oil composition.

Fully formulated lubricating oil compositions of the present inventionpreferably have a sulfated ash (SASH) content of about 1.9 mass % orless, preferably about 1.1 mass % or less, such as about 1.05 mass % orless.

The amount of phosphorus and sulfur are determined according to methodASTM D5185; “TBN” is Total Base Number as measured by ASTM D2896; theamount of nitrogen is determined according to method ASTM D4629; andsulfated ash is measured according to method ASTM D874.

Where the lubricating oil compositions of the present invention are forHDD use, the lubricating oil compositions preferably satisfy at leastthe performance requirements of the ACEA E2-96#5, more preferably atleast the ACEA E7-04 and/or API CI-4, such as at least the ACEA E4-99#3,especially at least the ACEA E6-04 and/or API CJ-4 specification. Wherethe lubricating oil compositions of the present invention are for PCDOuse, the lubricating oil compositions preferably satisfy at least theperformance requirements of the ACEA B2-98#2, more preferably at leastthe ACEA B3-04, such as at least the ACEA B4-04/ ACEA C3-04, especiallyat least the ACEA B5-04/ ACEA C3-04/ ACEA C2-04 specification(s). Wherethe lubricating oil compositions of the present invention are for PCMOuse, the lubricating oil compositions preferably satisfy at least theperformance requirements of the ACEA A2-96#3/ API SJ, more preferably atleast the ACEA A3-04/ ACEA C3-04, such as at least the API SL/ ILSACGF-3, especially at least the ACEA A5-04/ ACEA C2-04/ ACEA C3-04/ APISM/ ILSAC GF4 specification(s).

It should be appreciated that interaction may take place between any twoor more of the additives, including any two or more detergents, afterthey have been incorporated into the oil composition. The interactionmay take place in either the process of mixing or any subsequentcondition to which the composition is exposed, including the use of thecomposition in its working environment. Interactions may also take placewhen further auxiliary additives are added to the compositions of theinvention or with components of oil. Such interaction may includeinteraction which alters the chemical constitution of the additives.Thus, the compositions of the invention include compositions in whichinteraction, for example, between any of the additives, has occurred, aswell as compositions in which no interaction has occurred, for example,between the components mixed in the oil.

The lubricating oil compositions may be used to lubricate mechanicalengine components, particularly an internal combustion, such as acompression-ignited (diesel) engine, or a spark-ignited (gasoline)engine or a manual or automatic transmission unit, by adding thelubricating oil thereto and operating the engine/transmission.

In this specification the term “hydrocarbyl” as used herein means thatthe group concerned is primarily composed of hydrogen and carbon atomsand is bonded to the remainder of the molecule via a carbon atom, butdoes not exclude the presence of other atoms or groups in a proportioninsufficient to detract from the substantially hydrocarboncharacteristics of the group. The term “comprising” or “comprises” whenused herein is taken to specify the presence of stated features,integers, steps or components, but does not preclude the presence oraddition of one or more other features, integers, steps, components orgroups thereof. In the instance the term “comprising” or comprises” isused herein, the term “consisting essentially of” and its cognates are apreferred embodiment, while the term “consisting of” and its cognatesare a preferred embodiment of the term “consisting essentially of”. Theterm “oil-soluble” or “oil-dispersible”, as used herein, does not meanthat the additives are soluble, dissolvable, miscible or capable ofbeing suspended in the oil in all proportions. They do mean, however,that the additives are, for instance, soluble or stable dispersible inthe oil to an extent sufficient to exert their intended effect in theenvironment in which the oil composition is employed. Moreover, theadditional incorporation of other additives such as those describedabove may affect the solubility or dispersibility of the additives.“Major amount” means in excess of 50, such as greater than 70,preferably 75 to 97, especially 80 to 95 or 90, mass %, of thecomposition. “Minor amount” means less than 50, such as less than 30,for example, 3 to 25, preferably 5 or 10 to 20, mass %, of thecomposition mass % of the composition. All percentages reported are mass% on an active ingredient basis, i.e. without regard to carrier ordiluent oil, unless otherwise stated. The abbreviation SAE stands forSociety of Automotive Engineers, an organization that classifieslubricants by viscosity grades.

EXAMPLES

The invention will now be particularly described, by way of exampleonly, as follows:

Example 1

A lubricating oil composition representing a conventional 10W40crankcase lubricant for a heavy duty diesel engine meeting therequirements of the ACEA E4-99#3 specification was prepared by blendinga base stock oil of lubricating viscosity, a detergent/inhibitor (DI)package including salicylate detergent, dispersant, ZDDP andantifoamant; a viscosity modifier (VM) and lubricating oil flow improver(LOFI). The resulting composition had a nitrogen content of 0.1 mass %;a sulfur content of 0.3 mass %, a sulfated ash (SASH) content of 1.9mass %, 1250 ppm of phosphorus and 43 mmols of salicylate soap perkilogram of finished lubricant.

Four lubricating oil compositions were prepared based on the aboverecipe. Example 1, a comparative example, contained no added 450 M_(n),polybutene (PIB). Examples 2, 3 and 4, which represent the invention,contained 0.5, 1 and 2 mass % of 450 M_(n) PIB, respectively. The foursamples were then tested for compatibility with nitrile rubber using thebench tests 5 used by Mercedes Benz (MB) or Daimler Chrysler (DC),specifically Test Method VDA6753014; Maschinenfabrik Augsburg & Nürnberg(MAN), specifically Test Method DIN53521 (nitrile seal); and Motoren undTurbinen Union (MTU); specifically Test Method DIN53521 (for nitrileseals). The results are shown below in Table II. Where the tests wererepeated a number of times, an average result is provided. TABLE II Ex.1 Ex. 2 Ex. 3 Ex. 4 Bench Test Property Limit (0) (0.5) (1) (2) MBSEALNBR EAB* −35% max −45 −44 −37 TS** −20% max −20 −19 −11 V*** 0 to 10% 00 0 H**** −8 to +2 pts. 0 0 0 # of tests — >5 2 3 0 MANSEAL EAB −30% max−43 — −36 −32 NBR TS −20% max −23 — −12 −12 V 0 to +10% 2 — 2 2 H −10pts. max −1 — −1 −1 # of tests — >5 0 3 2 MTUSEAL EAB −35% max −40 −34−36 −33 NBR TS −20% max −23 −11 −16 −17 V 0 to 10% 2 2 2 2 H 0 to −10pts. −1 −1 −1 −2 # of tests — >5 2 2 2*elongation at break;**tensile strength;***volume;****hardness

As shown, in each of the bench tests, the addition of PIB resulted inimproved performance, particularly in terms of EAB and TS, sufficientlyto provide a passing result, where the base formulation failed.

Example 2

A lubricating oil composition representing a low SAPS (sulfated ash,phosphorus, sulfur) 10W40 crankcase lubricant for a heavy duty dieselengine meeting the requirements of the ACEA E6-04 specification wasprepared by blending a base stock oil of lubricating viscosity, adetergent/inhibitor (DI) package including salicylate detergent,dispersant, ZDDP and antifoamant; a viscosity modifier and LOFI (lubeoil flow improver). The resulting composition had a nitrogen content of0.16 mass %; a sulfur content of 0.25 mass %, a sulfated ash (SASH)content of 0.25 mass % and 800 ppm of phosphorus and 24 mmol ofsalicylate soap per kilogram of finished lubricant.

Four lubricating oil compositions were prepared based on the aboverecipe. Example 5, a comparative example, contained no added 450 M_(n)polybutene (PIB). Examples 2, 3 and 4, which represent the invention,contained 2.1, 2.5 and 3.0 mass % of 950 M_(n) PIB, respectively. Thefour samples were then tested for compatibility with nitrile rubber thebench tests described in Example 1. The results are shown below in TableIII. TABLE III Ex. 5 Ex. 6 Ex. 7 Ex. 8 Bench Test Property Limit (0)(2.1) (2.5) (3.0) MBSEAL NBR EAB* −35% max. −57 −31 −33 −27 TS** −20%max. −35 −11 −12 −11 V*** 0 to +10% 2 2 2 2 H**** −8 to +2 pts. 1 −2 1−1 MANSEAL NBR EAB −30% max. −55 −28 — −27 TS −20% max. −48 −10 — −10 V0 to +10% 5 5 — 5 H −10 pts. max −2 −3 — −4

As shown, the effects of the invention are particularly apparent in lowSAPS HDD lubricants formulated with salicylate detergents. Again, ineach of the bench tests, the addition of PIB resulted in improvedperformance, particularly in terms of EAB and TS, sufficiently toprovide a passing result, where the base formulation failed.

Example 3

A lubricating oil composition representing a 15W40 crankcase lubricantfor a heavy duty diesel engine meeting the requirements of the PC-10specification was prepared by blending a base stock oil of lubricatingviscosity, a detergent/inhibitor (DI) package including sulfonate andsulfurized phenate detergent, dispersant, ZDDP, a molybdenum-sulfurcompound, and antifoamant; a dispersant/viscosity modifier and LOFI(lube oil flow improver). The resulting composition had a sulfur contentof 0.31 mass %, a nitrogen content of 0.14, a SASH content of 0.94; 50ppm of molybdenum and 1000 ppm of phosphorus.

Four lubricating oil compositions were prepared based on the aboverecipe. Example 9, a comparative example, contained no added 950 M_(n)polybutene (PIB). Examples 10, 11 and 12, which represent the invention,contained 0.5, 1.0 and 2.0 mass % of 950 M_(n) PIB, respectively. Thefour samples were then tested for compatibility with nitrile rubber inthe bench tests described in Example 1. The results are shown below inTable IV. TABLE IV Bench Ex. 9 Ex. 10 Ex. 11 Ex. 12 Test Property Limit(0) (0.5) (1.0) (2.0) MBSEAL EAB* −35% max. −37 −29 −23 −21 NBR TS**−20% max. −18 −13 −9 −7 V*** 0 to +10% 2.1 2 2 2 H**** −8 to +2 pts. −2−2 −2 −2

As shown, the effects of the invention are also apparent in lubricantsformulated with phenate and sulfonate detergents. The addition of PIBresulted in improved performance, specifically in terms of EAB,sufficient to provide a passing result, where the base formulationfailed.

Example 4

Five lubricating oil compositions were prepared based on the recipeprovided in Example 3. Example 13, a comparative example, contained noadded 950 M_(n) polybutene (PIB). Examples 14, 15, 16 and 17, whichrepresent the invention, contained 2, 3, 4 and 5 mass % of 950 M_(n)PIB, respectively. The five samples were then tested for corrosion,particularly copper corrosion, using the High Temperature CorrosionBench Test described in ASTM D6594. The results are shown below in TableV. TABLE V Ex. 14 Ex. 15 Ex. 16 Ex. 12 Property Limit Ex. 13 (2) (3) (4)(5) Cu  20 max 111 24 13 12 9 Pb 120 max 44 36 37 38 42 Sn  50 max 0 2 22 2 Cu Strip  3 4B 1A 1A 1A 1A

As demonstrated, the addition of PIB to a lubricating oil compositioncontaining a significant sulfur content further improves coppercorrosion performance and allows passage of the HTCBT with a formulationthat fails the test in the absence of the PIB.

The disclosures of all patents, articles and other materials describedherein are hereby incorporated, in their entirety, into thisspecification by reference. A description of a composition comprising,consisting of, or consisting essentially of multiple specifiedcomponents, as presented herein and in the appended claims, should beconstrued to also encompass compositions made by admixing said multiplespecified components. The principles, preferred embodiments and modes ofoperation of the present invention have been described in the foregoingspecification. What applicants submit is their invention, however, isnot to be construed as limited to the particular embodiments disclosed,since the disclosed embodiments are regarded as illustrative rather thanlimiting. Changes may be made by those skilled in the art withoutdeparting from the spirit of the invention.

1. A method of improving copper corrosion properties and/or nitrile sealcompatibility in or with a lubricating oil composition comprising amajor amount of oil of lubricating viscosity and a minor amount of oneor more additives, said composition having a sulfur content of at least0.1 mass %, based on the total mass of lubricating oil composition,which method comprises adding to and/or incorporating into thelubricating oil composition an effective amount of at least onenon-hydrogenated polymer, preferably an olefin polymer or copolymer,such as polybutene and/or polyisobutene.
 2. The method of claim 1,wherein said effective amount is from 0.2 to 10.0 mass %, based on thetotal mass of said lubricating oil composition.
 3. The method of claim2, wherein said effective amount from 1.0 to 2.5 mass %, based on thetotal mass of said lubricating oil composition.
 4. The method of claim 1wherein the oil of lubricating viscosity has a sulfur content of from0.001 to 0.10 mass %, based on the total mass of oil of lubricatingviscosity, and optionally, at least one of the said additives comprisesa sulfur-containing compound providing at least 0.005 mass % sulfur,based on the mass of said composition.
 5. The method of claim 4 whereinthe oil of lubricating viscosity has a sulfur content of from 0.005 to0.05 mass %, based on the total mass of oil of lubricating viscosity,and optionally, at least one of the said additives comprises asulfur-containing compound providing at least 0.005 mass % sulfur, basedon the mass of said composition.
 6. The method of claim 1, wherein atleast one additive comprising a sulfur-containing compound is selectedfrom metal salts of dihydrocarbyl dithiophosphates, sulfonatedetergents, sulfurized phenate detergents, sulfur-containing molybdenumcompounds, ashless dithiocarbamates, and combinations thereof.
 7. Themethod of claim 1, wherein said lubricating oil composition has at leastone of (a) a sulphated ash (SASH) content of from 0.5 to 1.9 mass and(b) a phosphorus content of less than 1500 ppm, based on the total massof the composition.
 8. The method of claim 1, wherein said lubricatingoil composition comprises a salicylate detergent in an amount providingsaid composition with at least 9 mmoles of salicylate soap per kg ofsaid composition.
 9. The method of claim 1, wherein said lubricating oilcomposition comprises a nitrogen-containing dispersant and/ordispersant-viscosity modifier in an amount providing in said compositionfrom 0.08 to 0.35 mass % of nitrogen.
 10. The method of claim 1, whereinsaid lubricating oil composition has a phosphorus content of less than1500 ppm, based on the total mass of said composition.
 11. The method ofclaim 10, wherein said lubricating oil composition has a phosphoruscontent of from 500 to 1500 ppm, based on the total mass of saidcomposition.
 12. The method of claim 11, wherein said lubricating oilcomposition has a phosphorus content of less than 1200 ppm, based on thetotal mass of said composition.
 13. The method of claim 12, wherein saidlubricating oil composition has a phosphorus content of from 500 to 1200ppm, based on the total mass of said composition.
 14. The method ofclaim 13, wherein said lubricating oil composition has a phosphoruscontent of from 500 to 850 ppm, based on the total mass of saidcomposition.
 15. The method of claim 1, wherein said oil of lubricatingviscosity comprises at least 50 mass % of mineral oil, based on thetotal mass of said composition.
 16. The method of claim 1, wherein saidcomposition is a power transmission fluid or a crankcase lubricating oilcomposition for an internal combustion engine.
 17. The method of claim16,wherein said composition is a crankcase lubricating oil compositionfor an internal combustion heavy duty diesel (HDD) engine and saidcomposition meets the performance requirements of at least ACEA E2-96#5.18. The method of claim 16, wherein said composition is a crankcaselubricating oil composition for an internal combustion heavy duty diesel(HDD) engine and meets the performance requirements of at least one ofACEA E7-04 and API CI-4.
 19. The method of claim 16, wherein saidcomposition is a crankcase lubricating oil composition for an internalcombustion heavy duty diesel (HDD) engine and meets the performancerequirements of at least one of ACEA E6-04 and API CJ-4.
 20. The methodof claim 1, wherein the said non-hydrogenated (co-) polymer has a numberaverage molecular weight in the range of from 450 to
 2300. 21. Themethod of claim 20, wherein the said non-hydrogenated (co-) polymer hasa number average molecular weight in the range of from 450 to
 1300. 22.The method of claim 21, wherein the said non-hydrogenated (co-) polymerhas a number average molecular weight in the range of from 450 to 950.23. A lubricating oil composition comprising a sulfur content of atleast 0.15 mass %, comprising a major amount of an oil of lubricatingviscosity, a minor amount of additive(s) including at least one additivehaving sulfur content, and a minor amount of a non-hydrogenated olefinpolymer, and optionally, one or more of the following: (i) asulfur-containing additive selected from metal salts of dihydrocarbyldithiophosphates, sulfonate detergents, sulfurized phenate detergents,sulfur-containing molybdenum compounds, ashless dithiocarbamates, (ii) asulfated ash (SASH) content of from 0.5 to 1.9 mass % based on the massof the composition; (iii) a phosphorus content of less than 1500 ppm,(iv) a nitrogen-containing dispersant and/or dispersant-viscositymodifier providing from 0.08 to 0.35 mass % nitrogen in saidcomposition; and (v) a salicylate detergent providing at least 9 mmolsof salicylate soap per kilogram of composition.